engine overheats at 10 minutes of running

Well you have eliminated just about everything! It sounds like maybe the water pump is not working some how. Since you eliminated everything else perhaps taking the water pump out and making sure the impeller is still attached to the shaft would be something worth trying. Good luck!

I would retest the external thermostat. I recently replaced mine and began to have overheating problems. I put the new thermostat in a sauce pan on the stove and found it wouldn't open until the water was rapidly boiling. Too late. I put the old thermostat which was still functioning back in and the overheating problem went away.

Could be that the radiator fluid got pretty low and you had to add alot of coolant then failed to bleed off the air adequately. My Spider 2000's system was REALLY difficult to bleed. I had to try several methods suggested by fellow owners before I was successful. Some Fiat shop manuals go so far as to suggest drilling a small hole in the metal of the thermostat to allow proper bleeding off of air.

I have the same problem. I replaced the radiator,thermostat,fan,and water pump. Bled the air 3 times,It still gets hot after about 5 minutes.It has an electric fan.